Thermal imaging cameras are used in a variety of situations. For example, thermal imaging cameras are often used during maintenance inspections to thermally inspect equipment. Example equipment may include rotating machinery, electrical panels, or rows of circuit breakers, among other types of equipment. Thermal inspections can detect equipment hot spots such as overheating machinery or electrical components, helping to ensure timely repair or replacement of the overheating equipment before a more significant problem develops.
Thermal imaging cameras include sensors for detecting infrared energy in a scene being viewed by the camera. An example of such a sensor is a focal plane array (FPA) which generates an electrical signal in response to infrared energy received through the camera lens. The FPA includes sensor elements, such as bolometers or photon detectors, and each such sensor element may be referred to as a sensor pixel. The electrical resistance or voltage of the sensor pixels changes in response to infrared energy and can therefore be used to generate a thermal image.
The focal plane array includes a plurality of sensor pixels arranged side by side, often in vertical columns and horizontal rows. However, one or more sensor pixels may be inoperable or may become damaged during production of the FPA and prior to placement in the thermal imaging camera. In some cases, such as when only a single pixel is inoperable, the processor of the camera can compensate for the inoperable pixel by mathematical analysis of the data from the surrounding pixels to estimate the thermal energy reading that would be obtained by the inoperable sensor pixel if it were functioning normally, and use that estimate in producing the thermal image. However, in other cases, such as when multiple pixels which are adjacent to each other are inoperable, such an estimate of the thermal energy reading is less effective, resulting in a defect which may be perceptible and/or objectionable to a manufacturer or end user. In such cases, the manufacturer may choose to discard the FPA.
In some cases, if the defect is located on the periphery of the FPA, the thermal imaging camera may use only the central portion of the FPA for gathering thermal energy readings. In this way, the FPA can still be used, though a reduced number of sensor pixels would be used to create the thermal image. However, such adjustments are not possible if the defect is located too close to the center of the FPA. In addition, portions of the periphery of the FPA which are fully functional, or which include pixels for which mathematical compensation is acceptable, remain unused and are therefore wasted in such a scenario.